A known refrigerator for commercial use (for example, see Patent Document 1) has a function to perform a defrosting operation during intervals of a cooling operation. Specifically, an evaporator and an evaporator fan are equipped in a storage compartment. The evaporator is connected to a freezing device including a compressor. On the other hand, the evaporator is equipped with a defrost heater. At a time of the cooling operation, the compressor and the evaporator fan are driven to generate cool air around the evaporator. The cool air is circularly supplied to the storage compartment to cool the storage compartment. On the other hand, the defrosting operation is performed by supplying current to the defrost heater in a state where the compressor and the evaporator fan are stopped. During this time, the temperature of the evaporator is detected and, when it reaches a predetermined temperature, it is regarded that defrosting is completed, and then the defrost heater is turned off. Thus, the defrosting operation is terminated. Then, after a lapse of a predetermined drain time, the compressor is started up first and, subsequently after a predetermined delay time, the evaporator fan is started up. Thus, the cooling operation is restarted.
Here, during the defrosting operation, since the defrost heater heats the evaporator, the refrigerant pressure (lower pressure) in the cooling circuit is increased. Where the lower pressure is increased, high starting torque is necessary at the time of start-up of the compressor and, in an event that the voltage applied to the compressor is lower because of lower power-source voltage or the like, the compressor cannot be started up or can be started up only after repeats of switching operation of the starter that is one of start-up circuit parts for the compressor. This creates a problem of shortening the life of the starter.
[Patent Document 1] Japanese Unexamined Patent Application Publication No. 2005-300074
On the other hand, the refrigerator of this type is equipped with an anti-dew heater in portions such as a front frame where dew is possibly formed. These portions are thus heated by the anti-dew heater. However, it has turned out that the anti-dew heater, which is always supplied with current in known arts, exerts not a little influence in causing decrease of the voltage applied to the compressor at the time of start-up of the compressor.